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