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