One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,8)(3,6,4,7)(9,10,13,16)(11,14,19,17)(12,20,21,15)(18,23,24,22)(25,26,32,30)(27,36,35,31)(28,33,40,38)(29,34,39,37)(1,2)(3,6)(4,7)(5,8)(9,10)(11,14)(12,15)(13,16)(17,19)(18,22)(20,21)(23,24)(25,27)(26,31)(28,34)(29,33)(30,36)(32,35)(37,40)(38,39) involution — undirected(1,3,5,4)(2,6,8,7)(9,10)(11,14)(12,15)(13,16)(17,19)(18,22)(20,21)(23,24)(25,28)(26,33)(27,37)(29,36)(30,38)(31,39)(32,40)(34,35)(9,10)(11,17)(12,15)(13,16)(14,19)(18,23)(20,21)(22,24)(25,29,32,39)(26,34,30,37)(27,33,35,38)(28,36,40,31)(9,11)(10,14)(12,18)(13,19)(15,22)(16,17)(20,23)(21,24)(25,30,32,26)(27,36,35,31)(28,38,40,33)(29,34,39,37)(1,4,5,3)(2,7,8,6)(9,12,13,21)(10,15,16,20)(11,18,19,24)(14,22,17,23)(25,31,32,36)(26,35,30,27)(28,39,40,29)(33,34,38,37)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.