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