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