One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,8)(3,6,4,7)(9,10,14,17)(11,15,18,22)(12,13,16,21)(19,20,23,24)(25,26,32,31)(27,35,34,29)(28,38,30,33)(36,40,37,39)(1,2)(3,6)(4,7)(5,8)(9,11)(10,15)(12,19)(13,20)(14,18)(16,23)(17,22)(21,24)(25,27)(26,29)(28,36)(30,37)(31,35)(32,34)(33,40)(38,39) involution — undirected(11,18)(15,22)(19,23)(20,24)(25,28,32,30)(26,33,31,38)(27,36,34,37)(29,40,35,39)(9,11)(10,15)(12,19)(13,20)(14,18)(16,23)(17,22)(21,24)(25,29,32,35)(26,34,31,27)(28,39,30,40)(33,36,38,37)(1,3,5,4)(2,6,8,7)(9,12)(10,13)(11,19)(14,16)(15,20)(17,21)(18,23)(22,24)(25,30,32,28)(26,33,31,38)(27,37,34,36)(29,40,35,39)(1,4,5,3)(2,7,8,6)(9,13)(10,16)(11,20)(12,17)(14,21)(15,23)(18,24)(19,22)(25,31,32,26)(27,35,34,29)(28,38,30,33)(36,39,37,40)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.