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