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