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