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