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