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