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)(11,20)(12,26)(13,19)(14,18)(15,24)(16,29)(17,28)(21,34)(22,33)(23,25)(27,37)(30,36)(31,35)(32,38)(39,40) involution — undirected(1,3,4,8)(2,5,6,7)(9,11)(10,15)(12,27)(13,25)(14,24)(16,34)(17,23)(18,20)(19,33)(21,31)(22,28)(26,32)(29,40)(30,38)(35,39)(36,37)(9,12,28,31,14,30,13,29)(10,16,19,36,18,35,17,26)(11,21,22,38,24,40,25,27)(15,32,33,34,20,37,23,39)(2,6)(5,7)(9,13,14,28)(10,17,18,19)(11,22,24,25)(12,29,30,31)(15,33,20,23)(16,26,35,36)(21,38,40,27)(32,34,37,39)(3,8)(5,7)(9,10)(11,23)(12,16)(13,17)(14,18)(15,22)(19,28)(20,25)(21,39)(24,33)(26,29)(27,37)(30,35)(31,36)(32,38)(34,40) involution — undirectedA 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.