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