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