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