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