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