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