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